What Is Concrete Compressive Strength?
The concrete compressive test measures strength by loading standard samples, cast in moulds and cured, to failure. The result is found by dividing the failure load by the sample's cross-sectional area. Cube and cylinder samples give different values from the same concrete, so the sample type must always be stated in the report.
Purpose of Concrete Compressive Strength
The purpose is to determine whether the cast concrete meets the strength class specified in the project. Since compressive strength is related to many of concrete's other properties, it is the central parameter in structural inspection.
Which Products Is Concrete Compressive Strength Applied To?
- Ready-mix and site-batched concrete
- Precast concrete elements
- Concrete road and pavement surfaces
- Cast-in-place structural elements
- Core samples (from existing structures)
In Which Sectors Is Concrete Compressive Strength Used?
Standards Related to Concrete Compressive Strength
- EN 12390-3 (hardened concrete — compressive strength)
- EN 12390-1 / -2 (sample shape, dimensions and preparation)
- EN 12350-1 (sampling of fresh concrete)
- EN 206 / TS 13515 (concrete — specification, performance and conformity)
Concrete Compressive Strength Conditions
- Specimen type
- Standard cube or cylinder; size from standard
- Cure
- Samples are cured in water and temperature defined in the standard.
- Experimental age
- From the specification; fitness assessment is usually done at a certain age
- Loading speed
- Constant speed within the range given by the standard
Equipment for Concrete Compressive Strength
- Concrete press (compression testing machine)
- Curing tank or curing room
- Sample moulds and tamping rod
- Sample surface capping setup
- Calipers and balance
Sample Requirements for Concrete Compressive Strength
- The sample must be taken so as to represent the batch and in accordance with the sampling rules of the relevant standard.
- The sampling date, location and the person who took the sample must be recorded.
- Samples requiring curing or conditioning must be stored under the defined conditions.
- The number of samples must meet the minimum required by the standard.
- The sample must not be damaged during transport.
Duration of Concrete Compressive Strength
The test itself takes minutes. Curing time is the determining factor: samples are held in curing until the age defined in the standard for conformity assessment.
Concrete Compressive Strength Procedure
- 1A sample is taken from fresh concrete per the standard and placed in moulds.
- 2Samples are compacted and held in the mould for the defined duration.
- 3Samples removed from the mould are placed in curing.
- 4Samples reaching the test age are removed from curing and measured.
- 5Loading surfaces are capped if required.
- 6The sample is placed in the press and loaded at the defined rate.
- 7The failure load is recorded, strength calculated, and failure mode assessed.
Concrete Compressive Strength Acceptance Criteria
The acceptance class does not come from the test method but from the product standard and the project: concrete class, reinforcement class, aggregate category, or fire performance class is defined in the specification. The report gives the measured value; the conformity decision is made against the relevant product standard.
Evaluation of Results
The result is assessed against the concrete class specified in the project and the conformity rules of EN 206 / TS 13515. Assessment relies on a group of a defined number of samples, not a single sample. The failure mode must be one of the acceptable types in the standard; otherwise the result is questioned.
Concrete Compressive Strength Report
- Sample description, sampling location and date
- Sampling method and witness sample information, if any
- Standard and test conditions applied
- Sample dimensions, curing conditions and age information
- Measured values and calculated results
- Failure mode or damage description (where applicable)
- A statement that the result applies only to the specimen submitted for testing
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- EU 305/2011 Construction Products Regulation (CPR)
- Construction Products Regulation (Turkey)
- TS 500 / Requirements for Design and Construction of Reinforced Concrete Structures
- Turkish Building Earthquake Code
Construction Materials Testing — What Does This Testing Field Cover?
The section below describes the field that the Concrete Compressive Strength test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Construction materials testing shows whether a product performs the function it takes on within the structure. A wide field is gathered in this family, from the compressive strength of concrete to the thermal transmittance of glass, from sieve analysis of aggregate to the watertightness of windows.
What sets this family apart from the others is that the result turns directly into a REGULATORY DECLARATION. For products covered by construction products legislation a declaration of performance (DoP) is mandatory, and every essential characteristic in the declaration rests on a test result. Reaction-to-fire class, thermal conductivity, compressive strength, water permeability and release of dangerous substances are declared in this way. The declaration is a legal text carrying the manufacturer's signature; the test record behind it is the first document requested in an inspection.
The second distinguishing feature is that the product is assessed over its SERVICE LIFE. An electronic device runs for five years; a building component stays in place for fifty and is exposed throughout that time to freeze-thaw cycles, UV, moisture, chemical attack and load. Durability tests (freeze-thaw, carbonation, alkali-silica reaction, ageing) therefore carry as much weight in this field as classical strength tests.
Tests are separated by material type and each group has its own set of standards: cement and concrete, aggregate, masonry units, wood-based panels, thermal insulation, glass and glazing units, ceramic tiles, floor coverings, screeds, joint fillers and coating systems. Where the product will be installed determines which set applies — the same panel is assessed against different standards on a wall and on a floor.
Factory production control (FPC) is a continuous component of the field. CE marking on a construction product is not obtained with a single test and then left; the manufacturer must set up a system showing that it monitors production consistency, takes samples regularly and intervenes when there is a deviation. Depending on the product group, this system may have to be audited by a notified body.
Site testing is a separate body of work. In the laboratory the product is approved; on site it is checked that the product really is of the declared class and that it has been applied correctly. Fresh concrete slump, cylinder sampling, aggregate sieve analysis and in-situ watertightness tests fall within this scope.
Method groups in this field
Concrete and cement
Slump, air content and unit weight in fresh concrete; compressive and flexural strength, water permeability and freeze-thaw resistance in hardened concrete. For cement, compressive strength, setting time and composition analysis.
Aggregate
Sieve analysis, particle shape, Los Angeles abrasion resistance, freeze-thaw, alkali reactivity and density/water absorption.
Thermal and energy performance
Thermal conductivity and thermal resistance, calculation of thermal transmittance (U value) in glazing units, solar energy transmittance.
Facade and joinery
Air permeability, watertightness and wind load resistance in windows and doors; fire performance in facade systems.
Fire performance
Reaction-to-fire classification and fire resistance tests; these are two separate concepts and are addressed by separate standards.
Masonry, tile and flooring
Compressive strength, water absorption, abrasion resistance, slip resistance, stain and chemical resistance.
Emissions and dangerous substances
Formaldehyde release from wood-based panels, VOC emissions from construction products, leaching behaviour of aggregates and waste.
Commonly confused in this field
- REACTION to fire and RESISTANCE to fire are different concepts: one describes the material's contribution to a fire, the other how long a component holds the fire back.
- A declaration of performance is not a certificate; it is the manufacturer's declaration. Notified body involvement varies with the product group and the assessment system.
- A test result is valid for the mounting arrangement in which the product was tested. A different substrate, a different thickness or a different joint detail may require reassessment.
- A site sample and a laboratory sample are not the same thing. A concrete cylinder taken on site also reflects application and curing conditions; it does not replace product approval.
- ASTM and EN construction standards measure similar quantities with different specimens and scales; the results cannot be converted one-to-one.
Which decisions these results support
- Declaration of performance (DoP) and CE marking
- Establishing and maintaining the factory production control system
- On-site conformity control of concrete, aggregate and workmanship
- Meeting fire and energy performance requirements
- Verifying the technical items in the project and tender specification
Related Tests
Frequently Asked Questions About Concrete Compressive Strength
Why do cube and cylinder results differ?
The sample's height/width ratio and the friction effect in the press differ. A cylinder sample from the same concrete generally gives a lower value than a cube; the class definition is therefore only meaningful together with the sample type.
Is a core result assessed the same as a sample result?
No. A core taken from a structure is assessed against a different standard and does not directly give a production conformity decision; it shows the condition of the existing structure.